Various technologies for aiding a color-blind person who has impaired color vision in grasping the color of an image have been proposed. Patent Literature 1, for example, discloses a technology in which the color of an image transmitted from a user's portable terminal is analyzed and color data is transmitted to the portable terminal. Patent Literatures 2, 3, and 4 disclose technologies with which the color of a graph or text is presented in a form that can be identified by a color-blind person (e.g., color name).